We propose the study of the effects of structural changes upon the oxygen and carbon monoxide binding of single heme compounds. Our discovery of a simple heme derivative which reversibly binds oxygen makes this study possible. We will prepare crystalline oxygen and carbon monoxide for X-ray crystallography and Esea studies. Furthermore, studies of IR and nmr of these complexes in solution will be studied. The effects of variation in solvent, ligand basicity and strain upon the oxygen and carbon monoxide bonding and oxidation potentials will be explored. These results will help us to understand the ability of myoglobin and hemoglobin to reversibly bind oxygen and the structural effects responsible for the differences between the oxygen binding proteins, the cytochromes and oxidases.